The Crystalline Salts of Calcium Bilirubinate in Human Gallstones

1. The acid, neutral and ‘intermediate’ salts of calcium bilirubinate have been synthesized.

2. All are crystalline, and the intermediate salt which has 1½ molecules of bilirubin per calcium atom probably has a crystal structure containing molecules of both acid and neutral salts.

3. The acid or intermediate salts have been found in 14 out of 70 gallstones analysed recently by X-ray diffraction.